背景:犬流感病毒(CIV)的爆发引起了极大的关注,因为它对狗的健康构成了重大威胁。在小猎犬的H3N2CIV进化过程中,该病毒在2019年后形成了新的进化枝,并逐渐对其他哺乳动物更具适应性。因此,成功阐明其生物学特性并构建犬流感感染模型是CIV表征所必需的。
方法:我们进行了遗传分析以检查CIV的生物学特征和感染动力学。
结果:我们的H3N2CIV株(来自2019年上海)的基因型属于5.1支,现在在中国很普遍。使用MDCK细胞,我们调查了病毒性细胞病变的影响。使用透射电子显微镜观察病毒大小和形态。小猎犬也感染了104、105和10650%的鸡蛋感染剂量(EID50)。与其他组相比,106EID50组表现出最明显的临床症状,病毒滴度最高,典型的肺部病理改变。我们的结果表明,其他两种治疗方法均引起轻度的临床表现和病理变化。随后,通过苏木精和伊红(H&E)和免疫荧光(IF)染色检测106EID50组的CIV分布,这表明CIV主要感染了肺部。
结论:本研究建立的框架将指导进一步的CIV预防策略。
BACKGROUND: The canine influenza virus (CIV) outbreak has garnered considerable attention as it poses a significant threat to dog health. During the H3N2 CIV evolution in beagles, the virus formed a new clade after 2019 and gradually became more adaptable to other mammals. Therefore, successfully elucidating the biological characteristics and constructing a canine influenza infection model is required for CIV characterization.
METHODS: We performed genetic analyses to examine the biological characteristics and infection dynamics of CIV.
RESULTS: The genotype of our H3N2 CIV strain (from 2019 in Shanghai) belonged to the 5.1 clade, which is now prevalent in China. Using MDCK cells, we investigated viral cytopathic effects. Virus size and morphology were observed using transmission electron microscopy. Beagles were also infected with 104, 105, and 106 50% egg-infectious doses (EID50). When compared with the other groups, the 106 EID50 group showed the most obvious clinical symptoms, the highest virus titers, and typical lung pathological changes. Our results suggested that the other two treatments caused mild clinical manifestations and pathological changes. Subsequently, CIV distribution in the 106 EID50 group was detected by hematoxylin and eosin (H&E) and immunofluorescence (IF) staining, which indicated that CIV primarily infected the lungs.
CONCLUSIONS: The framework established in this study will guide further CIV prevention strategies.